Alliant 300-MP in 357 Magnum and Different Bullet Weights

[wasa]

I've been using Alliant Power Pro 300-MP in my Ruger Blackhawk with 125gr and 158gr jacketed bullets and am happy with the loads. I usually load about 1-2 grain below maximum listed with no negative indication on the cases or primers.

However, I would like to use other bullet weights (since I have many hundreds of them), but the only two published sources I have of loads (Alliant PDF/web and Hornady #9 manual) only list select bullet weights (example Alliant 125gr, 158gr, 170gr). There is nothing in my Lyman 48, and I see nothing listed online with Speer or Nosler bullets.

I have lots of 110gr, 140gr, and 150gr jacketed 0.357" projectiles that I would like to use. Does anyone know of a published source for this powder in 357 Mag for these bullets?

Alternatively, does anyone have experience interpolating to these bullets (yes, I know that I am responsible for my loads)?

Alliant lists

125gr - max 22.3gr
158gr - max 18.6gr
170gr - max 17.5gr

So, 22.3gr of 300-MP for 110gr may be reasonable. 18.6gr for 150gr or 140gr projectiles may be reasonable.

Thoughts?

 

[Blue68f100]

You can always use the next heavier bullet of similar construction weight and work up. A lot of times a mfg does not list the lighter bullets for a reason. It has to do with how the powder reacts to pressure. Does not build up to the necessary pressure for it to preform good. A lighter bullet does better with a little faster powder normally.

 

[RealGun]

I had that problem with 300-MP, and after a squib I decided to only use bullets that matched the data or change powders to match available data for my bullets. The best I found was Hornady and their XTPs, which shoot great.

 

[WrongHanded]

Handloader #274 has an article about 300-MP, including a 140gr XTP @ 18.5gr to 20.5gr.

 

[wasa]

Handloader #274 has an article about 300-MP, including a 140gr XTP @ 18.5gr to 20.5gr.

Thanks! My subscription started with Issue 315 and I like the magazine, but with the new online format it's really not my thing. Not sure if I will renew when it comes time. Will consider buying that one issue.